The overall goal of Project P-2 is to test the hypothesis that extracellular proteases are key determinants of the remodeling of the airway epithelium glands, extracellular matrix, and vasculature that contribute to the perpetuation of and morbidity from chronic airway inflammation. Dr. Caughey and his colleagues will address this issue by performing in vivo studies of selected proteases and their targets in genetically altered mice, including those infected with Mycoplasma pulmonis as a model of chronic airway disease, and in vitro studies of molecular behavior and targets of these proteases. Aim 1 is to determine the roles of proteinase-activated receptors (PARs) in airway remodeling, with a focus on thrombin and mast cell tryptase as activating ligands of PAR-1 and PAR-2, which may mediate growth-promoting effects of these proteases on airway glands and smooth muscle. The role of these receptors in airway remodeling will be examined by localization sites of PAR expression in normal and inflamed airways and exploring airway remodeling in PAR-null mice. Aim 2 is to explore roles of proteases in extracellular matrix remodeling in PAR-null mice. Aim 2 is to explore roles of proteases in extracellular matrix remodeling in chronic airway inflammation, seeking particularly to understand the importance of the matrix metalloproteinase gelatinase B and a thiol protease, dipeptidyl peptidase I. The laboratory's previous experiments suggest that both proteases are secreted and activated by mast cells, which may be an important source of these enzymes in airway remodeling. In these experiments we will localize proteases expression in airway microenvironments and examine mycoplasma-induced remodeling in gelatinase and dipeptidyl peptidase-null mice. Aim 3 is to explore the roles of mast cell proteases in vascular remodeling in airway inflammation, focusing on protease-mediated formation and degradation of angiogenic and angiostatic proteins. The approach here is to establish molecular mechanisms of angiotropic factor generation and to deficient mice. Understanding mechanisms underlying these changes may identify previously unexplored strategies to prevent or reverse anatomical changes accompanying chronic airway inflammation.